With the development of optical disc technology (compact discs, laser discs, DVD discs et.) their use has increased dramatically. Many different types of information are now stored on these types of discs which are used in the home, the workplace, in the automobile and with portable equipment.
The optical disc stores information digitally. The stored information is used by computers by reading tiny grooves and peaks as binary data. In audio CD players the Digital to Analog Converter (DAC) is used to turn the digital information to analog signals that can be heard as sound. Optical discs have two sides, the information side (generally the one with the label on it) and the read or play side (the shiny clear side). The preferred outer material in most of these discs is a poly-carbon. The poly-carbon encases the data layer and provides the shape and structural integrity for the disc. Due to the softness of poly-carbons however, surface damage is quite common. If the surface of an optical disc is scratched for example, the laser beam used to read the data is often reflected or misdirected resulting in mis-tracking or skipping.
The information side has a gloss coating that helps in protecting it, but the read side has no protection of any sort except for the jewel case, which only protects it during storage. Unfortunately most damages to the disc occurs during transition from the case to players or by mishandling. When a disc is damaged by scuffs or a scratch, the end result is loss of information. This translates to skipping and in some cases stopping of the disc playing device. In some audio CD players a technology called over-sampling is used to compensate for some information loss by filling in the missing data. This does help somewhat in allowing CDs to be still useable even with scuffs but it is very limited. In most cases over-sampling does not help in common types of scratches. This invention is designed to protect the CD by placing a protective cover on the read side where most of the damage occurs.
When being stored discs are typically placed in a rigid container (jewel case) which protects both the data side and the label side of the disc. When in use however the discs remain unprotected. Most of the damage occurs when discs are being transferred from storage to the reading/writing device.
Prior art devices do exist. Some require a centering adapter to ensure proper alignment. Others use adhesives, which can migrate off the surface or even to the disc which could damage the surface. Yet others are difficult to attach and remove.
A prior art device is disclosed in U.S. Pat. No. 4,983,437 entitled "Compact Disc Protector". This device only protects the information (top) side of the disc. The information side of the disc is generally more resilient to damage as compared to the unprotected play (bottom) side. The information side typically has a protective lacquer coating whereas the bottom side usually does not.
U.S. Pat. No. 4,879,710 entitled "Optical Disc Protector and Method for Applying Same" also discloses a protective device for optical discs. This device uses adhesive to attach the protector to the disc.
It would be desirable to have an easily attachable device that remains on the disc when in use and in storage. The protective device would have to permit normal functioning of the disc and would have to be capable of being securely attached. The ideal device would effectively be invisible to the user, providing added protection without any significant loss of convenience or utility.
The present invention overcomes problems associated with the prior art devices by providing protection to the read/play side of the disc and by allowing the end user to apply the device without the use of a special applying tool or adhesives. The use of adhesives may cause problems to the disc because of chemical reactions and also the migratory properties of adhesives. The end result is that the present invention will be easier to apply and will eliminate the use of any form of adhesives. Also because of the fact that it does not use adhesives, the present invention will be flexible and easier to replace if it incurs damage due to mishandling.
The prior art uses materials that were different from the CD itself. This could result in bubbling or the protective devices not fitting on to the CD properly due to thermal expansion or contraction. The present invention is designed to eliminate this problem by expanding or contracting at the same rate as the disc even at extreme temperature fluctuations. This ensures a precise fit for the protective device to the disc.